Oh yes, that does sound familiar. That's why you sneak up on them from 500 meters away and headshot them. Bit hard at that distance, but safer than getting closer to them. Lots of enemies were extremely dangerous at close range, so the game taught you to take your time, line up your shot and have an exit strategy for when things went tits up. Which it often did.You also had AI with wallhacks that would pre-fire an RPG at you before you even turned a corner, so it would hit and kill you the instant you appeared. All of this from ranges of over 200m. Otoh, sometimes if you rushed them around the corner you could stand 0.5 in front of them and they would crouch and be looking around frantically and not see you.... Btw., hats off to you, sir, for knowing that venerable game! There were also other in that series and using that engine (which was pretty unique cause it didn't use polygons like all other games).
Btw., ever played Joint Operations online? I absolutely freaking LOVED that game, was actually one of the games that got me into online gaming, together with America's Army.
But yeah, they'd almost have to have wallhacks, because that game only had like 32, maybe 64 megabytes of RAM to work with, so some concessions had to be made with processing their AI, especially on such a huge map.
Haven't heard of joint operations.